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/*
 * RTC driver for Maxim MAX8907
 *
 * Copyright (c) 2011-2012, NVIDIA Corporation.
 *
 * Based on drivers/rtc/rtc-max8925.c,
 * Copyright (C) 2009-2010 Marvell International Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/bcd.h>
#include <linux/i2c.h>
#include <linux/mfd/max8907.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/rtc.h>
#include <linux/slab.h>

enum {
	RTC_SEC = 0,
	RTC_MIN,
	RTC_HOUR,
	RTC_WEEKDAY,
	RTC_DATE,
	RTC_MONTH,
	RTC_YEAR1,
	RTC_YEAR2,
};

#define TIME_NUM			8
#define ALARM_1SEC			(1 << 7)
#define HOUR_12				(1 << 7)
#define HOUR_AM_PM			(1 << 5)
#define ALARM0_IRQ			(1 << 3)
#define ALARM1_IRQ			(1 << 2)
#define ALARM0_STATUS			(1 << 2)
#define ALARM1_STATUS			(1 << 1)

struct max8907_rtc {
	struct max8907		*max8907;
	struct regmap		*regmap;
	struct rtc_device	*rtc_dev;
	int			irq;
};

static irqreturn_t max8907_irq_handler(int irq, void *data)
{
	struct max8907_rtc *rtc = data;

	regmap_write(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0);

	rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);

	return IRQ_HANDLED;
}

static void regs_to_tm(u8 *regs, struct rtc_time *tm)
{
	tm->tm_year = bcd2bin(regs[RTC_YEAR2]) * 100 +
		bcd2bin(regs[RTC_YEAR1]) - 1900;
	tm->tm_mon = bcd2bin(regs[RTC_MONTH] & 0x1f) - 1;
	tm->tm_mday = bcd2bin(regs[RTC_DATE] & 0x3f);
	tm->tm_wday = (regs[RTC_WEEKDAY] & 0x07);
	if (regs[RTC_HOUR] & HOUR_12) {
		tm->tm_hour = bcd2bin(regs[RTC_HOUR] & 0x01f);
		if (tm->tm_hour == 12)
			tm->tm_hour = 0;
		if (regs[RTC_HOUR] & HOUR_AM_PM)
			tm->tm_hour += 12;
	} else {
		tm->tm_hour = bcd2bin(regs[RTC_HOUR] & 0x03f);
	}
	tm->tm_min = bcd2bin(regs[RTC_MIN] & 0x7f);
	tm->tm_sec = bcd2bin(regs[RTC_SEC] & 0x7f);
}

static void tm_to_regs(struct rtc_time *tm, u8 *regs)
{
	u8 high, low;

	high = (tm->tm_year + 1900) / 100;
	low = tm->tm_year % 100;
	regs[RTC_YEAR2] = bin2bcd(high);
	regs[RTC_YEAR1] = bin2bcd(low);
	regs[RTC_MONTH] = bin2bcd(tm->tm_mon + 1);
	regs[RTC_DATE] = bin2bcd(tm->tm_mday);
	regs[RTC_WEEKDAY] = tm->tm_wday;
	regs[RTC_HOUR] = bin2bcd(tm->tm_hour);
	regs[RTC_MIN] = bin2bcd(tm->tm_min);
	regs[RTC_SEC] = bin2bcd(tm->tm_sec);
}

static int max8907_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct max8907_rtc *rtc = dev_get_drvdata(dev);
	u8 regs[TIME_NUM];
	int ret;

	ret = regmap_bulk_read(rtc->regmap, MAX8907_REG_RTC_SEC, regs,
			       TIME_NUM);
	if (ret < 0)
		return ret;

	regs_to_tm(regs, tm);

	return 0;
}

static int max8907_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct max8907_rtc *rtc = dev_get_drvdata(dev);
	u8 regs[TIME_NUM];

	tm_to_regs(tm, regs);

	return regmap_bulk_write(rtc->regmap, MAX8907_REG_RTC_SEC, regs,
				 TIME_NUM);
}

static int max8907_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct max8907_rtc *rtc = dev_get_drvdata(dev);
	u8 regs[TIME_NUM];
	unsigned int val;
	int ret;

	ret = regmap_bulk_read(rtc->regmap, MAX8907_REG_ALARM0_SEC, regs,
			       TIME_NUM);
	if (ret < 0)
		return ret;

	regs_to_tm(regs, &alrm->time);

	ret = regmap_read(rtc->regmap, MAX8907_REG_ALARM0_CNTL, &val);
	if (ret < 0)
		return ret;

	alrm->enabled = !!(val & 0x7f);

	return 0;
}

static int max8907_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct max8907_rtc *rtc = dev_get_drvdata(dev);
	u8 regs[TIME_NUM];
	int ret;

	tm_to_regs(&alrm->time, regs);

	/* Disable alarm while we update the target time */
	ret = regmap_write(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0);
	if (ret < 0)
		return ret;

	ret = regmap_bulk_write(rtc->regmap, MAX8907_REG_ALARM0_SEC, regs,
				TIME_NUM);
	if (ret < 0)
		return ret;

	if (alrm->enabled)
		ret = regmap_write(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0x77);

	return ret;
}

static const struct rtc_class_ops max8907_rtc_ops = {
	.read_time	= max8907_rtc_read_time,
	.set_time	= max8907_rtc_set_time,
	.read_alarm	= max8907_rtc_read_alarm,
	.set_alarm	= max8907_rtc_set_alarm,
};

static int max8907_rtc_probe(struct platform_device *pdev)
{
	struct max8907 *max8907 = dev_get_drvdata(pdev->dev.parent);
	struct max8907_rtc *rtc;
	int ret;

	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
	if (!rtc)
		return -ENOMEM;
	platform_set_drvdata(pdev, rtc);

	rtc->max8907 = max8907;
	rtc->regmap = max8907->regmap_rtc;

	rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, "max8907-rtc",
					&max8907_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc->rtc_dev)) {
		ret = PTR_ERR(rtc->rtc_dev);
		dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
		return ret;
	}

	rtc->irq = regmap_irq_get_virq(max8907->irqc_rtc,
				       MAX8907_IRQ_RTC_ALARM0);
	if (rtc->irq < 0)
		return rtc->irq;

	ret = devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,
				max8907_irq_handler,
				IRQF_ONESHOT, "max8907-alarm0", rtc);
	if (ret < 0)
		dev_err(&pdev->dev, "Failed to request IRQ%d: %d\n",
			rtc->irq, ret);

	return ret;
}

static struct platform_driver max8907_rtc_driver = {
	.driver = {
		.name = "max8907-rtc",
	},
	.probe = max8907_rtc_probe,
};
module_platform_driver(max8907_rtc_driver);

MODULE_DESCRIPTION("Maxim MAX8907 RTC driver");
MODULE_LICENSE("GPL v2");